Even the most common medications pose threats

Karen Ravn

Some drugs are so common that consumers -- at their peril -- don't think twice about them. But each drug, whether prescription or over-the-counter, poses risks. To highlight these risks, we offer up a few details on five of the most-prescribed medications, with additional input from pharmacists interviewed for this package of stories.

Most serious risks: Abuse and addiction; acetaminophen overdose. Too much acetaminophen can cause severe liver damage, even death, but many patients aren't aware of this danger -- or of how many medications contain acetaminophen. Acetaminophen is the active ingredient in Tylenol, but it's also found in many other medications.

Common interactions: Barbiturate anesthetics (e.g., thiopental); cimetidine (Tagamet); antidepressants, including monoamine oxidase (MAO) inhibitors such as phenelzine (Nardil) and tricyclic antidepressants such as amitriptyline; sodium oxybate (GHB). These may lead to excessive sleepiness or create breathing difficulty.

And our pharmacists say . . . : This is probably one of the most abused drugs on the market. While taking this drug, avoid taking alcohol and other drugs that cause sleepiness. If you drive while taking it, you can be cited -- and convicted -- for driving under the influence. Check the labels of any other medications you are taking to see if they contain acetaminophen, and only take one source of acetaminophen at a time. Fluids and fiber can help prevent constipation, but you may also need to take laxatives. Taking this drug with food can reduce stomachache. The dizziness or drowsiness that can come with the drug can increase the risk of falls -- a serious danger for older people.

Lisinopril

Brand names: Prinivil, Zestril

Description: An ACE (angiotensin-converting enzyme) inhibitor, lisinopril improves blood flow by interfering with the production of angiotensin II, a substance that constricts blood vessels and releases hormones that raise blood pressure. It's prescribed for high blood pressure and heart failure and to improve survival chances after heart attacks.

Most serious risks: Birth defects if taken while pregnant; hyperkalemia, a condition caused by high levels of potassium that can lead to an irregular heartbeat; nausea; slow, weak or nonexistent pulse; and even heart attacks. It is a particular risk in patients with poor kidney function.

Possible side effects: Nagging dry cough, dizziness. Less common but more severe: swelling of the face and lips, difficulty swallowing or breathing, itchiness.

And our pharmacists say . . . : This medication should never be used by pregnant women. ACE inhibitors are generally less potent in African Americans. Also, studies have shown that when taking lisinopril (or other ACE inhibitors), African Americans are at increased risk for angioedema (swelling similar to hives but under the skin and potentially life-threatening). Seniors too are at higher risk for angioedema. Also, if seniors are taking a diuretic and then start taking lisinopril too, their blood pressure may drop too quickly. It's better to start with lisinopril and add the diuretic later. If you drink alcohol while taking lisinopril, that can also make your blood pressure drop too much. Because lisinopril suppresses your body's ability to quickly adjust blood pressure, you could faint if you jump out of bed or stand up too fast. Avoid potassium supplements or salt substitutes containing potassium.

Simvastatin

Brand name: Zocor

Description: Like other statins, simvastatin inhibits a particular liver enzyme (HMG Co-A reductase) to reduce the liver's capacity for making cholesterol. It's prescribed to reduce LDL cholesterol, often called "bad cholesterol."

Most serious risks: Birth defects if taken while pregnant; (rarely) rhabdomyolysis, a severe breakdown of skeletal muscle that can lead to acute renal failure and death should myoglobulin (a muscle protein) leak into the blood or urine (making urine dark).

Common interactions: Digoxin (digitalis), warfarin (Coumadin), gemfibrozil, niacin, cyclosporine, danazol, verapamil, amiodarone. Simvastatin may increase the effects of digoxin and warfarin. The other drugs -- as well as grapefruit or grapefruit juice -- may increase the risk of muscle cramping, myopathy (muscle disease) and rhabdomyolysis.

And our pharmacists say . . . : When taking this drug, stick to your cholesterol-lowering diet -- or you'll defeat the purpose. Take at the same time every day, preferably at night. Do not take while pregnant. Do not drink grapefruit juice or eat large amounts of grapefruit. Avoid alcohol, which can raise triglyceride levels and possibly damage your liver. Muscle-related side effects are more likely in the elderly than in younger patients, and they may be more serious in the elderly, since they're already declining in muscle strength. In addition, the link between statins and muscle pain is easy to miss in the elderly because they often have pain from other causes.

Levothyroxine

Brand names: Levothroid, Levoxyl, Synthroid, Unithroid

Description: A thyroid hormone, levothyroxine is prescribed for hypothyroidism, a condition in which the thyroid gland doesn't produce enough thyroid hormone.

Most serious risks: High blood pressure, even a heart attack, if the dose is too high -- or if someone with normal thyroid production takes it in an attempt to lose weight. The latter is especially dangerous for someone who's also using amphetamines.

Possible side effects: Side effects are relatively rare because this is the same chemical the thyroid itself makes. But if the dose is too low, you may continue to have symptoms of hypothyroidism (e.g., fatigue, sluggishness, unexplained weight gain). If the dose is too high, you may develop symptoms of hyperthyroidism (e.g., sudden weight loss, increased appetite, nervousness or anxiety). Tell your physician immediately if you have chest pain or a rapid or irregular heartbeat or pulse.

Common interactions: If you take insulin or other diabetes medications, the correct dosage may change if you start taking levothyroxine. Many other medications can also interact with levothyroxine, including non- prescription drugs, vitamins, minerals and herbal supplements.

And our pharmacists say . . . : Take once a day in the morning on an empty stomach 30 minutes before breakfast or other medications. If you take iron, calcium or antacids (e.g., Mylanta, Maalox), you should take them at least four hours after levothyroxine. Scheduling can be a problem for seniors who take medication for osteoporosis, which also has to be taken by itself before breakfast. Talk to your physician or pharmacist to set up a schedule to make sure you take both. Levothyroxine is usually taken for life, although the dosage may change. (Get an annual blood check to determine if you're at the right level.) Dosage may need adjustment during pregnancy. If you stop taking levothyroxine without medical supervision, serious complications can result. If you miss a dose accidentally, you can take it later in the day, but do not try to "make up" for it by taking an extra dose the next day. Small changes in your thyroid pill can cause large changes in thyroid levels in the blood. So you should continue to take the same brand that you start on and get stabilized on. Don't shop around and change brands from month to month. Hypothyroidism can cause cognitive difficulties, and some patients admitted to nursing homes with a diagnosis of dementia can be "cured" by taking levothyroxine.

Azithromycin

Brand names: Zithromax, Zitromax, Sumamed

Description: A macrolide antibiotic, azithromycin works by stopping the growth and reproduction of bacteria (as opposed to killing them directly). It's in the erythromycin family and can be taken by patients who are allergic to penicillin. It's prescribed for a wide range of bacterial infections.

Most serious risks: As are all antibiotics, the drug is completely ineffective against viral infections, yet it's often prescribed without testing to see if an infection is viral or bacterial. This leads to widespread overuse that contributes to the growth of resistant bacteria -- i.e., bacteria impervious to available antibiotics.

Common interactions: Azithromycin may interact with a number of medications. Tell your physician or pharmacist about any other medications you take -- including vitamins, nutritional supplements, herbal products and non-prescription drugs -- in case your doses need to be changed.

And our pharmacists say . . . : Azithromycin is usually taken once a day for one to five days. This is a big plus in comparison to another popular antibiotic, amoxicillin, which is usually taken for seven to 10 days. But as with amoxicillin and all other antibiotics, you can't stop taking it as soon as you start feeling better. You have to finish your prescription. Stopping early increases the risk that the infection could come back. If you take antacids (e.g., Maalox, Mylanta), take them at least two hours before, or four hours after, taking azithromycin. If you miss a dose, don't double up. Take the next dose on time and continue on schedule until the prescription is gone. When patients with viral infections take an antibiotic, they may feel better four or five days later and assume it has worked -- but really the infection has just run its course.

ABOUT OUR PHARMACISTS: The following pharmacists shared their expertise for this story: Kathy Besinque, associate professor at the USC School of Pharmacy; Steven Chen, associate professor at the USC School of Pharmacy; Armon Neel Jr., geriatrics pharmacist in Griffin, Ga.; Ken Thai, owner of El Monte Pharmacy in El Monte; Bradley Williams, geriatrics pharmacist and professor at the USC School of Pharmacy.

FOR MORE INFORMATION:

This is just the tip of the iceberg when it comes to drug effects, side effects, interactions and all the other information available about how, why and when medications work.

* Drugs.com at azithromycin. This drug information site offers easy-to-read content for both professionals and consumers. For efficient searching, start by clicking on "Drugs A to Z."

* RxList at . This site also offers information for both professionals and consumers; start with "Drugs A-Z." Check out the "Pill Identifier." It's surprising how often this can be useful.

* The Food and Drug Administration at www.fda.gov "> www.fda.gov . The federal agency that approves prescription drugs offers more information than most consumers may ever need. The trick is in sorting through it. From the home page, click "Drugs" at the top left. On the next page, look for the "Drugs@FDA" link in the "Spotlight" box.